Diversidade de Culicidae durante os períodos crepusculares em bioma de Floresta Atlântica e paridade de Anopheles cruzii (Diptera: Culicidae)

Assemblage variation of mosquitoes (Diptera: Culicidae) in different land use and activity periods within a lowland tropical forest matrix in Campeche, Mexico

Most mosquito species are active during a certain part of the day, but climatic factors such as light intensity and relative humidity play an important role in the control of their activity. We selected three types of land use that were sampled in state of Campeche in 2018 (low semi-evergreen forest, secondary low semi-evergreen forest, and mango plantation), using ten CDC light traps baited with CO₂ , that were active during nine hours of three activity periods (dawn, noon, and nightfall). A GLM was used to investigate changes in the assembly of mosquitoes between different types of land use and temporal variations. Rank abundance curves were used to detect changes in the spatial and activity period of the mosquitoes and we then calculated the Exponential Shannon Index. A total of 6,110 mosquitoes belonging to 23 species were captured. The greatest richness and abundance were found in the secondary low semi-evergreen forest, with greater richness and lower abundance than the mango plantation which showed more abundance. Of the activity periods, dusk had the greatest abundance and richness followed by dawn and finally noon.

Effects of anthropogenic landscape changes on the abundance and acrodendrophily of Anopheles (Kerteszia) cruzii, the main vector of malaria parasites in the Atlantic Forest in Brazil

Background

The mosquito Anopheles (Kerteszia) cruzii is the main vector of human and simian malaria in the Atlantic Forest. This species is usually abundant in the forests where it occurs, preferring to live and feed on canopies, behaviour known as acrodendrophily. However, in several studies and locations this species has been observed in high density near the ground in the forest. In this study, it was hypothesized that factors associated with anthropogenic landscape changes may be responsible for the variation in abundance and acrodendrophily observed in An. cruzii.

Methods

The study was conducted in a conservation unit in the city of São Paulo, Brazil. Monthly entomological collections were performed from March 2015 to April 2017, and the resulting data were used with data from another study conducted in the same area between May 2009 and June 2010. Mosquitoes were collected from five sites using CDC and Shannon traps. Landscape composition and configuration metrics were measured, and generalized linear mixed-effect models were used to investigate the relationship between these metrics and variations in the abundance and acrodendrophily of An. cruzii.

Results

The model that showed the best fit for the relationship between landscape metrics and An. cruzii abundance suggests that an increase in the proportion of forest cover leads to an increase in the abundance of this mosquito, while the model that best explained variations in An. cruzii acrodendrophily suggests that an increase in total forest-edge length leads to greater activity by this species at ground level.

Conclusion

While the data indicate that changes in landscape due to human activities lead to a reduction in An. cruzii abundance, such changes may increase the contact rate between this species and humans living on the edges of forest fragments where An. cruzii is found. Future studies should, therefore, seek to elucidate the effect of these landscape changes on the dynamics of Plasmodium transmission in the Atlantic Forest, which according to some studies includes the participation of simian hosts.

Electronic supplementary material

The online version of this article (10.1186/s12936-019-2744-8) contains supplementary material, which is available to authorized users.

Mosquitoes (Diptera: Culicidae) from crepuscular period in an Atlantic Forest area in Southern Brazil

Abstract Crepuscular period is one of the factors that may influence the biting activity of mosquitoes. Many of these insects have a peak activity in this period. The purpose of this study was to investigate the afternoon crepuscular activity of Culicidae in a remaining area of Atlantic Forest in western Santa Catarina, southern Brazil. Moreover, the possible influence of abiotic factors, the abundance and species richness were verified. In order to better analyze the influence of crepuscular period in specific composition and abundance of mosquitoes, the dusk was divided into three periods: pre-sunset, sunset and post-sunset. At the end of the study, nine hundred and eight four specimens distributed in 12 genera and 23 species were collected. Trichoprosopon pallidiventer (Lutz, 1905) (59.76%), Aedes crinifer (Theobald, 1903) (8.13%), Ae. scapularis (Rondani, 1848) (5.89%) were the most abundant species. Spring time presented the greatest abundance and species richness. During the study, among the three periods evaluated, pre-sunset had the greatest abundance and post-sunset the lowest. Pre-sunset and sunset had the greatest similarity between species. Regarding to the abiotic factors evaluated seven and 15 days before sampling, they did not present significant correlation for the three most abundant species. However, temperature had a positive correlation to these species. Moreover, the correlation between collected species and its possible role as vectors of etiological agents of diseases was discussed.

Diversity of mosquito vectors (Diptera: culicidae) in caxiuanã, pará, Brazil

This paper presents a study based on ecological parameters represented by diversity and richness indices applied in a community of mosquitoes (Diptera: Culicidae), at the National Forest of Caxiuanã, Melgaço municipality, state of Pará, in the Brazilian Amazon. A total of 25,433 specimens of culicids were collected in the study, from five field collection periods, over 10 months, between 2005 and 2006. Specimens were collected in four heights of the forest (ground level, 8 m, 16 m, and 30 m-canopy). Diversity indices of Shannon and Berger-Parker were obtained, and indicators of dominance of species were calculated. The species Culex portesi was dominant in this site, representing about 84% of specimens. Measures of richness and similarity (Jaccard) were obtained for the five strata of time and four height levels. According to the richness estimator abundance-based covered estimator (ACE) the greatest value occurred in April (2006), considering the levels of height to 16 m and on the ground. The estimates obtained have shown quantitative parameters of mosquito populations in the region of the Forest of Caxiuanã.

Ecological aspects of mosquitoes (Diptera: Culicidae) in an Atlantic forest area on the north coast of Rio Grande do Sul State, Brazil

Mosquito diversity was determined in an area located on the southern limit of the Atlantic Forest on the north coast of Rio Grande of Sul State. Our major objective was to verify the composition, diversity, and temporal distribution of the mosquito fauna, and the influence of temperature and rainfall. Samplings were performed monthly between December, 2006 and December, 2008, in three biotopes: forest, urban area, and transition area, using CDC light traps and a Nasci vacuum. A total of 2,376 specimens was collected, from which 1,766 (74.32%) were identified as 55 different species belonging to ten genera. Culex lygrus, Aedes serratus, and Aedes nubilus were dominant (eudominant) and constant throughout samplings. The forest environment presented the highest species dominance (D(S) =0.20), while the transition area showed the highest values of diversity (H'=2.55) and evenness (J'=0.85). These two environments were the most similar, according to the Morisita-Horn Index (I(M-H) =0.35). Bootstrap estimates showed that 87.3% of the species occurring in the region were detected. The seasonal pattern showed a greater abundance of mosquitoes between May and October, indicating the period to intensify entomological surveillance in that area.

Anofelinos de Santa Catarina (Diptera: Culicidae), Brasil

INTRODUÇÃO: No Brasil, a Região Amazônica é endêmica em malária. Em Santa Catarina, a malária foi eliminada na década de 80. A partir daí, ocorreram poucos casos autóctones isolados, e esporádicos. No entanto, em função da existência do vetor em seu território, da existência de extensa área endêmica no Brasil e da grande mobilidade de pessoas em áreas turísticas no estado, existe a probabilidade de reintrodução da doença. MÉTODOS: Utilizou-se os seguintes dados: Banco de Dados do Núcleo de Entomologia da Fundação Nacional de Saúde, Santa Catarina (ACCES,1997-2000); Sistema de Informação de Vigilância Epidemiológica, Secretaria de Vigilância em Saúde (Malária/SC) e Sistema de Informação de Notificação e Agravo(SINAN/SC). Os mesmos foram transportados e analisados, no programa Microsoft Office Excel 2007. RESULTADOS: As coletas foram realizadas em 48 municípios, 159 localidades, sendo identificados 12.310 Culicídeos, 11.546 (93,7%) Anopheles e 764 (6,2%) como outros. Foram identificados três subgêneros e 13 espécies de anofelinos. CONCLUSÕES: Considerando que nos municípios pesquisados, foi identificada a presença de importantes vetores como Anopheles cruzii e Anopheles albitasis e há circulação de pessoas infectadas provenientes de áreas endêmicas, pode-se considerar que os mesmos são áreas receptivas e vulneráveis à malária. Essas espécies são suspeitas de serem responsáveis pela transmissão de malária na região, principalmente nos municípios de Gaspar, Indaial e Rodeio.

[Anopheles cruzii larvae found in bromelias in an urban area on the Brazilian coast]

The occurrence of Anopheles (Kerteszia) cruzii larvae is reported for the first time in bromelias on the ground located in an urban area within the municipality of Ilha Bela, on the northern coast of the State of São Paulo. From March 1998 to July 1999 312 immature forms of An. cruzii were captured, being that 8.6% of them were in bromelias in the urban environment, 40.1% in periurban bromelias and 51.3% in the forest. The average number of bromelias containing An. cruzii was 4.0% of the total investigated. The positive rate in the periurban and forested environments presented similar values. The presence of An. cruzii is probably due to their having been present previously in the forest, together with the frequent presence of these breeding places, food sources and appropriate shelter in the urban area. This set of factors makes it necessary to warn against the possibility of transferring infections from one environment to the other.

New records of mosquito species (Diptera: Culicidae) for Santa Catarina and Paraná (Brazil)

We provide eight new mosquito species records for Santa Catarina (Limatus flavisetosus Oliveira Castro 1935, Mansonia flaveola (Coquillett 1906), Ma. titillans (Walker 1848), Psorophora forceps Cerqueira 1939, Sabethes xyphydes Harbach 1994, Toxorhynchites bambusicolus (Lutz & Neiva 1913), Tx. theobaldi (Dyar & Knab 1906) and Wyeomyia lassalli Bonne-Wepster & Bonne 1921) and three for Paraná (Ochlerotatus argyrothorax Bonne-Wepster & Bonne 1920, Uranotaenia pallidoventer Theobald 1903 and Wyeomyia pilicauda Root 1928). Additionally, we list all species in these eight genera recorded previously in the two states. The known distribution and possible epidemiological implications of the new species records are discussed.